I bought my betta fish from a reputable aquarium store several months ago, and he was very happy, active, curious, and friendly. But he recently got sick from accidental overfeeding (despite me knowing better than that because I've had bettas before). I caught it early and went through the steps to help him recover, and he did! Because he got lethargic while he was sick, he seems to have lost muscle and has trouble holding up his tail now. He is clearly frustrated by it and therefore is still content with staying at the bottom of his tank or propping his tail up on a plant and resting there rather than swimming around. Most of the time when he swims now, it's in bursts, likely to keep his tail from dragging him down too much. He also still hasn't eaten much since I fasted him 2 weeks ago. His coloring is fine (his body is peach and his fins/face are red), his scales are flat, his fins are healthy looking, he is not constipated anymore, and he is still making little bubble nests at night. He will still interact (I got him to look up at me pretty easily for the second picture, which I just took), and his fins have the capability to be flared (in the pictures, he just has them down. They're not clamped). He seems healthy, despite the lack of eating. Do you have any tips on how I can re-engage him in swimming more or if there is another underlying issue that is plaguing him?